19.2.
Object

An object is an instance of a class. In the UML metamodel
Object is a sub-class of
Instance. Within a sequence diagram objects may be
used to represent a specific instance of a class. Unlike
collaboration diagrams (see Chapter 21, Collaboration Diagram Model Element Reference
), sequence diagrams cannot show generic behavior between
classifier roles.

An object is represented on a sequence diagram in ArgoUML
as a plain box labeled with the object name (if any) and class
name, separated by a colon (:). As links with stimuli to and
from other objects are added, a time line grows down from the
object. This is thin where the object does not have control and
thick where it does.

Caution

The current release of ArgoUML shows interactions
between objects, although the UML standard for sequence
diagrams is for interaction between instances of any
classifier).

However the actual implementation in ArgoUML permits
any classifier to be used with the object, and so the diagram
can successfully represent instances of actors for example as
well as classes.

Standard tab. The values for the bounds of the
object notionally define the bounding box of the object
and its time line. However if you change them it will
have no effect, and the original values will be reset
when you next revisit the tab.

Source

Standard tab, but with no contents.

Caution

An object should not generate any code, so
having this tab active is probably a mistake.

Tagged Values

Standard tab. In the UML metamodel,
Object has the following standard tagged
values defined.

persistence (from the
superclass, Instance. Showing
the permanence of the state information associated
with the object. Values
transitory (state is destroyed when the
object is destroyed) and
persistent (state is preserved when the
object is destroyed).

derived (from the
superclass, ModelElement).
Values true, meaning the object
is redundant -it can be formally derived from other
elements, or false meaning it
cannot.

Note

Derived objects still have their value in
analysis and design to introduce useful names or
concepts, and in design to avoid
re-computation.

Note

The UML Element metaclass
from which all other model elements are derived includes
the tagged element documentation
which is handled by the documentation
tab under ArgoUML

Checklist

Standard tab for a Classifier.

19.2.2.
Object Property Toolbar

Go up

Navigate up through the package structure.

New Stereotype

This creates a new Stereotype (see
Section 16.6, “
Stereotype
”) for the selected
object, navigating immediately to the properties tab
for that stereotype.

Delete

This deletes the object from the model

Warning

This is a deletion from the model
not just the diagram. To delete
an object from the diagram, but keep it within the
model, use the main menu Remove From
Diagram (or press the Delete key).

19.2.3.
Property Fields For Object

Name

Text box. The name of the object. By convention
object names start with a lower case letter and use
bumpy caps to divide words within the name.

Note

ArgoUML does not enforce this naming
convention.

Stereotype

Drop down selector. Object has no stereotypes by
default in the UML standard.

Text box. Records the namespace for the object.
This is the package hierarchy.

Stimuli Sent

Text area. Lists the stimuli sent to this
object.

Stimuli Received

Text area. Lists the stimuli received by this
object.

Classifier

Drop down selector. The name of the classifier of
which this is an object.

Caution

In the current release of ArgoUML the drop down
selector will include all
classifiers (i.e. interfaces, actors, use cases and
datatypes as well), which is what is wanted on the
diagram, although it should properly be called an
instance, rather than an object. In practice only
instances of classes and actors make much
sense.

Note

In the current release of ArgoUML the same
graphical presentation is used, even if the object is
actually representing an instance of an actor (when a
stick-man would be more usual).